Study On The Influence Of Three Benzotriazole Derivatives Inhibitor On Sulfur Corrosion Of Transformer Oil

Transformer failure caused by sulfur corrosion in oil-paper insulation attracts great attention of domestic and foreign researchers. In order to study the influence of corrosion inhibitor BTA、TTA and Irgamet 39 on sulfur corrosion of transformer oil, a series of accelerated thermal aging tests was car ried on new transformer oil by the addition of corrosive sulfur and three benzotriazole derivatives inhibitor in the laboratory. The surface state, microstructure and elements component of copper winding and insulation paper were analyzed by macroscopic observation and scanning electron microscope(SEM) together with energy-dispersive X-ray(EDX) analyzer; the breakdown voltage, dielectric loss and volume resistivity of transformer oil after thermal aging tests were measured by insulating oil dielectric str ength automatic tester and insulating oil dielectric loss and resistivity tester; electrochemical analysis of copper windings were measured by the three electrode electrochemical system, and compare the inhibition effect of three kinds of corrosion inhibitiors. The main research results of this paper are as follows:① The addition of corrosive sulfur DBDS can accelerate the corrosion of copper winding significantly, corrosion pits can be observed on the copper surface obvious, the deposition of copper sulfur compounds also can detected on the surface of copper winding and insulation paper; the corrosion effect of DBDS was inhibited after join the three benzene azole inhibitor, copper winding and insulation paper surface is smooth and no deposition of copper sulfur compounds. The copper winding and insulation paper surface conditions after the addition of Irgamet 39 are better than the other two kinds of corrosion inhibitors for the new copper winding, the surface state of the specimen add BTA close to which add TTA; for the surface morphology of corroded copper, the inhibition effect of BTA was superior to that of the other two inhibitors.② The addition of DBDS can decrease the capacitance arc diameter of the Nyquist curve which signs the corrosion resistance of copper winding, while the capacitance arc diameter of the Nyquist curve were significantly increased after add benzotriazole derivatives inhibitor. The capacitance arc diameter of the Nyquist curve is similar after the addition of corrosion inhibitor TTA and Irgamet 39 in the new copper sample, and 30%-40% larger than the addition of corrosion inhibitor BTA; the capacitance arc diameter of the Nyquist curve is the biggest after add BTA in the corroded copper. For the Tafel curve of the copper winding, t he corrosion potential decreased and the corrosion current density increases after the addition of DBDS, the self corrosion potential of copper winding remain stable after the addition of corrosion inhibitor and even slightly higher than the blank sample, the self corrosion current density was less than the blank sample; in the three kinds of corrosion inhibitor, the corrosion potential is the smallest and the corrosion current density is the biggest after the addition of BTA, followed by TTA and Irgamet 39.③ The addition of corrosive sulfur DBDS will seriously damage the insulation strength in all directions, while the addition of benzotriazole derivatives inhibitor can block the damage very well. From the view of corrosion inhibition effect of the new copper windings, Irgamet 39 has the best comprehensive performance, BTA is close to TTA, but TTA is slightly better. From the view of corrosion inhibition effect of the corroded copper windings, BTA has the best comprehensive performance, then followed by TTA and Irgamet 39. In determining the degree of sulfur corrosion condition of transformer oil, we can protect copper windings from corrosion by a reasonable choice of corrosion inhibitor which is more effective, and make a contribution to the safe and stable operation of power transformer and power grid finally.